Super-rigidity for CR embeddings of real hypersurfaces into hyperquadrics

We consider holomorphic mappings sending a given Levi-nondegenerate pseudoconcave hypersurface M in Cn+1 into a nondegenerate hyperquadric of the same signature in PCN+1 and show that if M is sufficiently close to a hyperquadric in a certain sense, then any two such mappings differ only by an automorphism of the hyperquadric.     

PECVD法制备SiO_xN_y膜Ⅰ—Ⅴ特性和击穿机理的测试分析

对等离子体增强化学汽相起积（PECVD）法制成SiOxNy薄膜组成的MIS结构样品，由集成测试系统测量Ⅰ－Ⅴ特性，用晶体管特性图示仪测试击穿行为。分析研究了该薄膜的Ⅰ－Ⅴ特性和击穿机理，探讨了膜的击穿电场及其随混合气体比例、反应空气压、衬底工作温度的变化关系。     

W_9Mo_3Cr_4V钢脉冲放电强化涂层激光熔覆的研究

采用ＸＲＤ和ＴＥＭ等现代分析手段研究了Ｗ９Ｍｏ３Ｃｒ４Ｖ高速钢脉冲放电ＹＧ８强化涂层激光熔覆后的组织与表面硬度变化。结果表明，经适当的激光熔覆后，试样表面硬度可达ＨＶ０．１１６００～１８００。分析认为，获得如此高硬度的主要原因是Ｗ２Ｃ和ＷＣ等高硬相及纳米晶组织的形成。     

Formation of InAs quantum dots and wetting layers in GaAs and AlAs analyzed by cross-sectional scanning tunneling microscopy

We have used cross-sectional scanning-tunneling microscopy (X-STM) to compare the formation of self-assembled InAs quantum dots (QDs) and wetting layers on AlAs (1 0 0) and GaAs (1 0 0) surfaces. On AlAs we find a larger QD density and smaller QD size than for QDs grown on GaAs under the same growth conditions (500 °C substrate temperature and 1.9 ML indium deposition). The QDs grown on GaAs show both a normal and a lateral gradient in the indium distribution whereas the QDs grown on AlAs show only a normal gradient. The wetting layers on GaAs and AlAs do not show significant differences in their composition profiles. We suggest that the segregation of the wetting layer is mainly strain-driven, whereas the formation of the QDs is also determined by growth kinetics. We have determined the indium composition of the QDs by fitting it to the measured outward relaxation and lattice constant profile of the cleaved surface using a three-dimensional finite element calculation based on elasticity theory.     

关于严实Hilbert环

在本文中，严实Ｈｉｌｂｅｒｔ环得到了更进一步的刻划．本文的主要结果是：一个环Ａ是严实Ｈｉｌｂｅｒｔ环，当且仅当多项式环Ａ［Ｘ］的每个实极大理想在Ａ上的局限是Ａ的一个极大理想，当且仅当Ａ是实Ｈｉｌｂｅｒｔ环，且Ａ［Ｘ］的每个实极大理想是极大的．     

On the uniqueness of the equilibrium state for an interacting fermion gas at high temperatures and low densities

Starting from bounded local perturbations, we release the spatial cutoff and prove the uniqueness of the KMS state at high temperatures and low densities for the continuous fermion system with pair-interaction proposed by Narnhofer and Thirring.     

V／F变换器与单片机实现的智能化高精度A／D转换器

文章主要介绍了Ｖ／Ｆ变换器与单片机相结合实现的高精度、高分辨率、低成本、隔离式Ａ／Ｄ转换器的接口技术。在阐述设计方法的同时，给出了实用电路和Ａ／Ｄ转换流程框图。     

H.263视频编码算法原理及DSP实现

介绍ITU-T H.263视频编码器在德州仪器（Texas Instruments)公司新一代数字信号处理芯片IMS320C6000上的实时实现技术。编程实现了H.263标准的主要内容及H.263 中提出的新的编码技术，重点讨论了H.263编码在TMS320C6711 DSP上的优化和实现。     

Fe3Al／Q235异种材料真空扩散焊界面物理力学性能研究

利用激光云纹干涉法对Fe3Al/Q235异种材料真空扩散焊界面物理力学性能进行了研究,介绍了其实测试件的工作原理、实验技术,测得了U场V场原始条纹图,U场V场包络位相图,U场V场三维位移网络图.分析了实验结果,并对扩散焊界面的几何变形情况作力学分析,得到了其物理力学信息.对Fe3Al/Q235异种材料的应用具有重要的理论和实际意义.     

Modeling catalytic reduction of NO by ammonia over V2O5

Preservation of the natural environment and therefore elimination of pollutants has become a major concern in the present world. NO_x is efficiently removed from the gas exhausts produced by fixed plants by the selective catalytic reduction processes where NO_x is reduced by ammonia. Despite the wide use of this process, many aspects concerning the reaction mechanism are still poorly understood. The reaction is very exothermic but requires a catalyst. Here we report the present status of the proposed mechanisms for the selective catalytic reduction of NO by ammonia on V₂O₅/titania catalyst. The discussion is centered on the last decade and focuses on new theoretical findings in the field. We provide ab initio calculations based on cluster and periodic models to analyze the adsorption of the reactants in reduced, oxidized and stoichiometric surfaces, assuming dry and wet conditions, to evaluate the intermediates proposed in the literature. Several conditions are settled to propose an active catalyst. Coadsorption is investigated and in dry conditions quasi spontaneous reaction is obtained on an oxidized catalyst when the model includes NO and NH₃ and is allowed easy hydration-dehydration processes. We conclude that adsorption of reactants takes place on reactive O sites provided by the catalyst, V₂O₅ dispersed on TiO₂–anatase phase. Dispersion is essential to generate reactive O atoms necessary for a good catalytic activity. Finally, we propose a new pathway to proceed in oxidizing conditions. Results are compared to recent theoretical calculations and to experimental data.